Type bar head for typewriters having an interchangeable type block

ABSTRACT

A type bar head for typewriters is provided with an interchangeable typeblock formed in a single piece of flexible plastic material covered with a deposit of metal. The type block is provided with a pair of flanges having a pair of wedge shaped projections engaging two chamfered edges of the type bar to block the type block in a direction perpendicular to the printing surface and with a resilient tongue between the flanges to lock the type block in a direction parallel to the printing surface.

United States Patent Albrile [451 Mar. 28, 1972 [54] TYPE BAR HEAD FORTYPEWRITERS 2,862,592 12/1958 Redmond ..197/36 HAVING AN INTERCHANGEABLE2,975,881 3/1961 Delponte et a1. ..l97/36 TYPE BLOCK 3,101,141 8/1963Canny ....l97/36 3,308,916 3/1967 Canny et al..... ....l97/36 [72]Inventor: Walter Albrile, Tonno, Italy 3,381,788 5/1968 Meisner et al.....197/36 3 432 018 3/1969 Watanabe et a1.. ..197/36 73 A l tt ssigneengo C Olive 1 & C S p A Tormo, Italy 3,434,867 3/1969 Rousselot 197/52 X[22] Filed: July 22, 1969 FOREIGN PATENTS OR APPLICATIONS [21] Appl.No.: 843,571

9,836 11/1910 Great Britain ....197/36 955,111 1 1950 F ..I97 36 [30]Foreign Application Priority Data fame July 22, 1968 Italy ..s2544 A/68Primary Examiner-Edgar Burr Attorney-Irons, Birch, Swindler, McKie &Beckett [52] U.S. Cl ..197/36 51 Int. Cl. ..B4lj1/02 ABSTRACT [58] FieldofSearch ..197/36, 52 A type bar head for typewriters is provided withan terchangeable typeblock formed in a single piece of flexible [56]References cued plastic material covered with a deposit of metal. Thetype UNITED STATES PATENTS block is provided with a pair of flangeshaving a pair of wedge shaped pl'OjECllOl'lS engaging two chamferededges of the type BUSZ 1 bar to block the type block in a directionperpendicular to the 1,189,522 7/ 1916 Anderson 197/36 printing surfaceand with a resilient tongue between the 1,206,972 12/1916 Anderson..197/36 fl to lock the type block in a direction parallel to the1,357,573 11/1920 Lee ..l97/36 priming Surface 2,171,470 8/1939Munoz.... .....197/36 2,446,360 8/1948 Clark 197/36 X 3 Claims, 3Drawing Figures 1 ll 1 7 u 21 8 Ll' 1 2'5 9 F" I n1 v11 u 11 26- 23 I I'19 PATENTEDHARZB I972 3.651.913

INVENTOR. WALTER ALBRI LE TYPE BAR HEAD FOR TYPEWRITERS HAVING ANINTERCHANGEABLE TYPE BLOCK BACKGROUND OF THE INVENTION 1. Field of theinvention The present invention relates to an interchangeable type blockfor the type bars of a type writing or other such machine in which typebars cooperate with a platen to effect printing. The type block isformed with a slot adapted to he slipped over the head of the type bar.

2. Description of the prior art Various type bars with interchangeabletypes are known. In one known type bar, the head of the bar is in theform of a resilient fork, so as to lock the type slipped on to it.Exchange of the type is rather difficult, however, since it is necessaryto bend the two arms of the fork while the type is slipped off.

In another known type bar, the type is formed by a metal plate bent inthe shape of a U. The plate is provided with stamped projections forlocking it on the head of the type bar. The type is excessivelycumbersome in width, however, so that the type plate must be suitablyslotted.

SUMMARY OF THE INVENTION The object of the present invention is toprovide a type block which is easily interchangeable, of low cost andhas the minimum width dimension. According to the invention, the blockis formed with a slot open on the side remote from the type or types andhaving projections or recesses in the slot which provide surfacesadapted, when the block is mounted on the head of the type bar, tocooperate with complementary surfaces of the head to resist movement ofthe block in at least two substantially perpendicular directions.

The invention will be described in more detail, by way of example, withreference to the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a median section of a typebar with an exchangeable type block embodying the invention;

FIG. 2 is a section on the line II II of FIG. 1;

FIG. 3 is an exploded perspective view of the type bar.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, thereference 5 indicates the terminal portion of a type bar of a typewriting machine, which is provided with the usual projection 6 adaptedto engage the type guide, which is not shown in the drawing. The typebar 5 is provided with a head 7 on which there is mounted a type blockindicated generally by the reference 8. On ,a substantially plane frontsurface 9 the block 8 carries two types 10 and 11.

The block 8 is provided with a slot 12 (FIG. 2) which is open on theside remote from the types and adapted to be slipped over the head 7 ofthe type bar 5, the slot being defined by two lateral flanges l3 and 14of very slender thickness which may range between 0.4 and 0.8 mm. Theblock 8 is provided at the top with a second resilient tongue 15(FIG. 1) separated from the flanges 13 and 14 by a slot 16 and adaptedto cooperate with a shaped edge 17 of the head 7 of the type bar 5 andwith a top edge 27 of each of the flanges l3 and 14 (FIG. 3). That is,edge 17 provides a fulcrum about which tongue or lever 15 may pivot tolift the slot in the block 8 out of engagement with the type bar.

The type bar 5 is provided with a first shoulder 18 adapted to act as anabutment for a bottom edge 19 of the block 8 to locate the block in adirection parallel to the front surface 9 and, therefore, to the writingsurface of the types 10 and 11. That is, abutment of edge 19 withshoulder 18 prevents further downward longitudinal motion of type block8.

A first resilient tongue 20 extends from the base of the slot 12perpendicularly to the surface 9. The tongue 20 is adapted to cooperatewith another shoulder 21 of the type bar 5 in such manner as to retainthe block 8 in the direction parallel to the surface 9, i.e., furtherupward longitudinal movement of the block is prevented by the abutmentof these two surfaces. Thus, the shoulders 18 and 21, along with edge 19and tongue 20, respectively, serve to prevent longitudinal motion of theblock, when it is in place on the type bar head.

The head 7 of the type bar 5 is moreover provided with two edges 22formed from the rearwardly facing edge of the type bar and perpendicularto the two shoulders 18 and 21, these two edges being chamfered at 45.The block 8, in turn, is provided in its slot 12 with two wedge-shapedlugs 23 projecting from each of the flanges 13 and 14. Each lug 23 has aface 24 inclined at 45 and adapted to cooperate with one of thechamfered edges 22 of the head 7 of the type bar 5. The cooperation ofthe lugs with the chamfered edges serves to prevent rearward lateralmotion perpendicular to the writing surface. Moreover, in the slot 12there are provided two upper projections 25 and two lower projections 26adapted to embrace the head 7 of type bar 5 and to be urged resilientlyagainst the lateral surface of the head itself by virtue of bending ofthe block to prevent forward lateral motion. Thus, motion by the typeblock in a direction perpendicular to the writing surface is prevented.

The type block 8 is preferably formed in a single piece and ispreferably made of high-strength plastics material, for examplepolyacetal resin known by the Trade Mark Hostafom" which is produced bythe German company Hoechst. The block 8 formed of this material ismetallized by means of a first chemical deposit of copper, a followingelectrolytic deposit of copper, an electrolytic depost of nickel and,finally, an electrolytic deposit of chromium, which gives the outersurface the hardness necessary for clear writing and for long life.

To remove the block 8 from the head 7, the tongue 15 is pressed with afinger so as to urge it first of all against the edge 17. By continuingto exert pressure, the tongue 15 bears against the edges 27 of theflanges l3 and 14, thus forcing the block 8 outwards and disengaging thetongue 20 from the shoulder 2 1.

To re-mount the block 8 on the head 7, the block 8 is forced with twofingers, acting simultaneously on the tongue 15 and on the surface 9,until the tongue 20 is inserted below the shoulder 21 and the lugs 23snap behind the chamfered edges 22.

What I claim is:

1. In a type bar head for typewriters and the like constituted by a typebar and a removable type block wherein the type block is achannel-shaped member formed from a type surface member and a pair ofrelatively flexible flanges extending perpendicularly from opposite endsof said type surface defining a substantially U-shaped slot opening onthe side of said type block remote from said type surface, said slotbeing constructed to receive said type bar, the improvement comprismg:

a surface on said type bar and an opposed surface on said type block,said surface and said opposed surface being positioned on said type barand said type block, respectively, as to abut each other when said typebar is engaged in said slot, the abutment of said surface and saidopposed surface preventing motion of said type block relative to saidtype bar in a first direction parallel to the plane of said type surfaceand longitudinally of said type bar,

shoulder means on said type bar and first flexible tongue meansextending from said type block inwardly of said slot, andperpendicularly to the plane of said type surface, said shoulder meansand said first flexible tongue means being positioned on said type barand said type block, respectively, as to abut each other when said typebar is engaged in said slot, the abutment of said shoulder means andsaid tongue means preventing motion of said type block relative to saidtype bar in a second direction parallel to the plane of said typesurface and longitudinally of said type bar,

a pair of outwardly facing chamfered surfaces formed on edges of a sideof said type bar remote from said type surface and longitudinallyextending parallel to said type surface,

a pair of opposed projections integral with said flange membersextending inwardly of said slot and having inclined surfaces arrangedfor cooperating with said chamfered surfaces so that said chamferedsurfaces and said inclined surfaces are in abutment when said type baris engaged in said slot, the abutment of said chamfered surfaces andsaid inclined surfaces preventing motion of said type block relative tosaid type bar in a direction perpendicular to said type surface,

shaped edge means formed on said type bar and forming a fulcrum-likemember and second flexible tongue rneans mounted on said type block in aposition as to be manually depressable against said block is formed in asingle piece of flexible plastics material covered with a deposit ofmetal.

3. A type bar head according to claim 1, having another pair ofprojections in the interior of said slot adapted to be forced by bendingagainst the lateral surfaces of the head of the type bar.

1. In a type bar head for typewriters and the like constituted by a typebar and a removable type block wherein the type block is achannel-shaped member formed from a type surface member and a pair ofrelatively flexible flanges extending perpendicularly from opposite endsof said type surface defining a substantially U-shaped slot opening onthe side of said type blOck remote from said type surface, said slotbeing constructed to receive said type bar, the improvement comprising:a surface on said type bar and an opposed surface on said type block,said surface and said opposed surface being positioned on said type barand said type block, respectively, as to abut each other when said typebar is engaged in said slot, the abutment of said surface and saidopposed surface preventing motion of said type block relative to saidtype bar in a first direction parallel to the plane of said type surfaceand longitudinally of said type bar, shoulder means on said type bar andfirst flexible tongue means extending from said type block inwardly ofsaid slot, and perpendicularly to the plane of said type surface, saidshoulder means and said first flexible tongue means being positioned onsaid type bar and said type block, respectively, as to abut each otherwhen said type bar is engaged in said slot, the abutment of saidshoulder means and said tongue means preventing motion of said typeblock relative to said type bar in a second direction parallel to theplane of said type surface and longitudinally of said type bar, a pairof outwardly facing chamfered surfaces formed on edges of a side of saidtype bar remote from said type surface and longitudinally extendingparallel to said type surface, a pair of opposed projections integralwith said flange members extending inwardly of said slot and havinginclined surfaces arranged for cooperating with said chamfered surfacesso that said chamfered surfaces and said inclined surfaces are inabutment when said type bar is engaged in said slot, the abutment ofsaid chamfered surfaces and said inclined surfaces preventing motion ofsaid type block relative to said type bar in a direction perpendicularto said type surface, shaped edge means formed on said type bar andforming a fulcrumlike member and second flexible tongue means mounted onsaid type block in a position as to be manually depressable against saidshaped edge means and then against another portion of said type block,said second tongue means being caused to pivot about said shaped edgemeans lifting said slot out of engagement with said type bar therebyfacilitating removal of said type block from said type bar.
 2. A typebar head according to claim 1, wherein said type block is formed in asingle piece of flexible plastics material covered with a deposit ofmetal.
 3. A type bar head according to claim 1, having another pair ofprojections in the interior of said slot adapted to be forced by bendingagainst the lateral surfaces of the head of the type bar.